Depends if we are talking defense or offense.
On defense, nothing comes close to grenade launchers for me. Z-mirrors come second I suppose, but when you watch a wave of 1600 laser gattlings go from 1600 to 0 within a single interface refresh, that's a good feeling.
On offense, it would have to be Zenith Bombards. I like playing the range game, dreadnaughts are always my first starship unlock and these fit me almost perfectly.
D.